Web tension control



March 22. 9 .1. BZDELIK, JR, ETAL 3,241,734

WEB TENS ION CONTROL FIG. 1

3 Sheets-Sheet 1 Filed May 1, 1963 INVENTORS Joseph Bzdelzlc, J

BY Paul S. Colecchi 7 figs March 1966 J. BZDELIK, JR, ETAL 3,241,784

WEB TENSION CONTROL 3 Sheets-Sheet 2 Filed May 1, 1963 r. mw 5 INVENTORS Joseph Bzde lzk J 511111 5. Colecclu' g! M EZi' S pm i March 1966 J. BZDELIK, JR., ETAL 3,241,784

WEB TENSION CONTROL Filed May 1, 1963 3 Sheets-Sheet 5 I VENTOR5 Jaseplz zdeZz'k,Jr:

BY Paul S. Colecchzl @lffiys United States Patent 3,241,784 WEB TENSION CONTROL Joseph Bzdelik, Jr., Morton Grove, and Paul S. Colecchi,

Chicago, Ill., assignors to A. E. Dick Company, Chicago, 11]., a corporation of Illinois Filed May 1, 1963, Ser. No. 277,286 4 Claims. (Cl. 242--75.43)

This invention relates to an apparatus of the type employing a continuous length of material to be used for the recording of information. In particular, the invention is directed to a means for controlling the tension in a web of such material during the recording operation.

There are many instances where the continuous recording of information over a relatively long period of time is required. In a typical recording system, a continuous length of printing material such as a paper web is moved past a recording device and the web is then recovered with the desired information displayed thereon.

In several important applications requiring printing devices of this nature, graphical representations are required. Thus, the printing medium employed may be provided with horizontal and vertical lines and the information recorded thereon will assume various positions relative to the lines on a graph. The recorded information may comprise a continuous line which defines a more or less wavy shape as the paper moves through the recording apparatus. In studying the recorded information at some later date, the position of the recorded line relative to the original lines on the graph will give information regarding certain functions.

In graphical representations of the type described, very small dimensional values often represent significant differences in the results recorded on the graph. Accordingly, it is very important that the paper or other recording material method have a constant tension applied thereto as the recording operation is being carried out. Variations in tension will result in variations in the amount of stretch in the recording material and such variations can significantly affect the information which is to be gathered from the recording operation.

It is the principle object of this invention to provide a mechanism in a recording apparatus which is adapted to maintain constant tension in a continuous length of recording material being passed through the apparatus.

It is a more specific object of this invention to provide a tension control means of the type described which is suitable for use in combination with continuous webs of printing paper which are to have information recorded thereon by means of an electrostatic printing tube.

These and other objects of this invention will appear hereinafter and for purposes of illustration but not of limitation, specific embodiments of this invention are shown in the accompanying drawings in which:

FIGURE 1 is a schematic illustration of a recording apparatus which advantageously utilizes the tension control means of this invention;

FIGURE 2 is a detail front elevational view of the tension control means of this invention;

FIGURE 3 is a side elevational view of the mechanism shown in FIGURE 2;

FIGURE 4 is a vertical sectional view of the mechanism shown in FIGURE 2; and,

FIGURE 5 is a cross sectional view taken about the line 5-5 of FIGURE 4.

The apparatus of this invention which is to be employed in a recording apparatus comprises a unique guide means for recording material being passed through the apparatus. The guide means operates in a completely mechanical fashion to control the operation of the drive mechanism which drives the recording material past the device which is utilized for recording the information.

The mechanism of this invention more particularly comprises a drive roller which is movable in response to the force applied by the web of printing material being driven through the apparatus. In the event that the force applied by the printing material varies at any time during the recording operation, to thereby move the drive roller, means associated with the drive roller are adapted to be operated to compensate for the change in force and to thereby maintain the tension in the printing web at a constant level.

The accompanying drawings illustrate a recording apparatus 10 which comprises a supply roll 12 of printing material, an electrostatic printing tube 14, a liquid developing means 16, a drying section 18, a cutoff means 20, and a receiving tray 22 for the finished material. The illustrated apparatus is adapted to employ a takeup reel 24 as an alternative to the use of the cutoff means 20 and tray 22. A source of liquid developer 26 is associated with a suitable pumping means (not shown) whereby the developing means 16 will be continuously supplied with fresh developing material. The section 28 of the apparatus may contain various electronic devices which control the information delivered to the electrostatic printing tube.

In a typical sequence of operation of a device such as shown in FIGURE 1, the web 30 of printing paper is passed over guide rollers 32, guide means 34, and then over guide roll 36 whereby it will be passed between the face of the electrostatic printing tube and the grounding back bar 38. Liquid developer for developing the latent image on the web is applied by roller 40 and excess developer is removed by means of roller 42. Guide roller 44 directs the web through the drying station 18 which may be provided with infra-red lamps 46. The rollers 48 and 50 comprise the primary drive rollers which act to draw the web through the apparatus.

The guide roller 34 comprises the web engaging member which acts to regulate the tension in the web as it passes through the apparatus. As shown in FIGURES 2 through 5, the roller 34 comprises an outer cylinder rotatable on bearing means 52 about a shaft 54. The shaft 54 is fixed to a vertically movable member 56 located behind the front wall 58 of the apparatus. A pin 60 extends through an opening defined in the end of the shaft 54 and wheels 62, which are tied to the pin, cooperate with the pin to secure the shaft 54 to the member 56. The member 56 defines an opening 66 which receives a post 68 attached to mounting members 70 whereby the post will be held stationary relative to the wall 58. The member 56 is adapted to be moved vertically up and down a track which is formed by the post 68. The opening 72 defined in the wall 58 permits movement of the roller 34 and shaft 54 corresponding to the vertical movement of the member 56. The wheels 62 ride on hearing plates 74 during vertical movement of the member 56 to permit smooth movement thereof. Bushings 76 are received at either end of the opening 66 defined in the member 56 to keep the member 56 properly aligned relative to the post 63. With this mounting arrangement, the cantilever mounting of the roller 34- can be achieved while maintaining the roller at all times in the same plane.

An outwardly extending member 78 is secured to the member 56 to provide a holding means for cam roller 80. The cam roller 80 is adapted to ride on the inner edge of cam lever 82. This cam lever is pivotally connected at 84 to the bracket 86 while the lower end of the cam lever is received in the bracket 88. This bracket comprises a bifurcated member having laterally extending pins 90 extending across its end whereby the movement of the cam lever will be restricted.

The upper end of the cam lever is provided with an extension 92 and a cable 94 is tied to this extension at 96. The cable extends around a pulley 98 which is rotatably mounted on the bracket 100. A second pulley 102 for the cable is mounted on a bracket 104 and the cable extends downwardly from this pulley where it is connected at 106 to a lever 108. The lever 108 is pivotally mounted at 110 and a spring 112 normally urges the lever in a counterclockwise direction about this pivot. The spring 112 is connected to a post 114 secured to the wall 58. A brake band 116 is connected at each end to pins 118 and 120 which are fixed to the lever 108. The brake band 116 extends around brake drum 122 which is fixed on the shaft 124. As shown in FIGURE 1, the shaft 124 is provided for mounting of the paper supply roll 12.

In the use of the apparatus of this invention, paper from the roll 12 can be threaded through the apparatus and the paper can be held at its leading end whereby the roller 34 will be supported at some intermediate level. When the drive rollers 48 and 50 are started, the roller 34 will seek its own level in accordance with the amount of resistance normally applied by the brake band 116. Thus, the supply roll 12 will present a drag in the system which will result in force being applied by the paper web to the roller 34 whereby the roller will be held at an intermediate level, for example at the level shown in the dotted line position of FIGURE 1.

The guide roller 34 will maintain this level as long as the tension exerted by the paper web remains constant. However, if this tension is increased, the roller 34 would begin to rise. Accordingly, the member 56 will rise whereby the cam follower 80 will move the cam lever 82 in the direction shown by the dotted line position in FIGURE 3. If the cam lever moves in this direction, the cable 94 will cause the lever 108 to be pivoted in a clockwise direction thereby loosening the brake band 116. This will have the effect of relieving a portion of the drag exerted by the paper supply roll 12 and the tension in the web will thus decrease until upward movement of the roller 34 ceases.

It will be apparent that any conditions causing a reduction in tension in the web 30 will result in lowering of the guide roller 34 and tightening of the brake band 116 whereby the drag by the paper supply roll will increase to thereby restore the web tension to the desired level. It has been found in practice that the actual movement of the roller 34 in the course of the running of a paper roll is barely perceptible. Thus, the construction described above has proven to be extremely sensitive to even minor changes in tension which necessarily arise in the course of running a long web of printing paper. The sensitivity of the device is such that the roller 34 will initially seek a given level and will maintain this level insofar as visual observations are concerned. Thus, fluctuations which normally characterize comparable devices of the type described have not been found to exist with the construction of this invention.

In the course of some recording operations, unusual defects in a paper roll or some other unusual occurrence may cause the paper web to split at some point between the supply roll 12 and the primary drive rolls 48 and 50. The tension control means of this invention allows for this situation by providing a plate 126 near the lower end of the post 68, and by providing a spring 128 beneath this plate. Accordingly, when the relatively heavy member 56 drops down due to separation of the paper web, a cushion for the member 56 is provided. The member 56 also carries a switch actuating tongue 130 which operates to actuate switch 132 in the event that the member 56 should drop down. The switch 132 is utilized to stop the drive means for the apparatus when actuated to decrease the posibility of damage to portions of the web which have recorded material thereon.

It will be understood that various changes and modifications can be made in the above described apparatus which provide the characteristics of this invention without departing from the spirit thereof particularly as defined in the following claims.

That which is claimed is:

1. In a recording apparatus wherein means are provided for continuously moving a supply of recording material past means for recording information on said material and including means positioned on opposite sides of said recording means for engaging said material and for maintaining tension in the material, the improvement comprising a guide roller disposed intermediate said tension maintaining means, a vertical track and a vertically movable member connected to one end of said guide roller and movable on said track, said guide roller being attached only at said one end whereby it is supported in cantilever fashion by said movable member, said movable member comprising a relatively heavy member defining a vertical guideway, a stationary vertical post received an said guideway to control the path of movement of said member, means on said member engaging a stationary surface defined in said apparatus and resilient means mounted at the lower end of said post to provide a custion for said vertically movable member if the member is suddently dropped due to a release of force applied by said printing paper, said movable member permitting shifting of the guide roller vertically from one position to another in response to forces applied thereto by said material, brake means and means connecting said brake means to one of said tension maintaining means, and means operatively connected to said guide roller for operating said brake means in response to vertical shifting movement of the guide roller and for thereby varying the tension applied to said material as said guide roller shifts positions, the means connecting the guide roller and brake means comprising a cam follower secured to said movable member, a cam lever adapted to be moved by said follower as said roller shifts positions, and a cable connected to said cam lever and to said brake whereby movement of said lever operates said brake means through said cable.

2. An apparatus in accordance with claim 1 wherein said brake is of the type comprising a drum tied to a shaft which controls the movement of said material through said apparatus, a band fitted around said drum, and wherein said band is connected to a pivotally mounted lever, said cable being connected to said pivotally mounted lever whereby said band can be tightened and loosened by said cable.

3. An apparatus in accordance with claim 1 wherein said guide roller extends outwardly from a vertical wall with said movable member being disposed on the opposite side of said wall, a vertical slot defined in said wall permitting vertical movement of said guide roller and said movable member, and including a supply roller which also extends outwardly of said wall with the brake means being connected to said supply roller and with the brake means being located on said opposite side of the wall, the shaft of said supply roller extending through said wall for association with said brake means.

4. An apparatus in accordance with claim 3 including a switch actuating means attached to said vertically movable member, and a switch adapted to be actuated by said actuating means when said vertically movable member drops down to engage said resilient means, said switch being adapted to shut off the means driving the paper through said apparatus.

References Cited by the Examiner UNITED STATES PATENTS 954,089 4/1910 Goss 24275.43 1,395,830 11/1921 Jones 24275.43 1,829,337 10/1931 Brueshaber 242-75.43 1,859,577 5/1932 Armbrecht 24275.43 3,116,032 12/1963 Roberts 242-75.43

MERVIN STEIN, Primary Examiner. 

1. IN A RECORDING APPARATUS WHEREIN MEANS ARE PROVIDED FOR CONTINUOUSLY MOVING A SUPPLY OF RECORDING MATERIAL PAST MEANS FOR RECORDING INFORMATION ON SAID MATERIAL AND INCLUDING MEANS POSITIONED ON OPPOSITE SIDES OF SAID RECORDING MEANS FOR ENGAGING SAID MATERIAL AND FOR MAINTAINING TENSION IN THE MATERIAL, THE IMPROVEMENT COMPRISING A GUIDE ROLLER DISPOSED INTERMEDIATE SAID TENSION MAINTAINING MEANS, A VERTICAL TRACK AND A VERTICALLY MOVABLE MEMBER CONNECTED TO ONE END OF SAID GUIDE ROLLER AND MOVABLE ON SAID TRACK, SAID GUIDE ROLLER BEING ATTACHED ONLY AT SAID ONE END WHEREBY IT IS SUPPORTED IN CANTILEVER FASHION BY SAID MOVABLE MEMBER, SAID MOVABLE MEMBER COMPRISING A RELATIVELY HEAVY MEMBER DEFINING A VERTICAL GUIDEWAY, A STATIONARY VERTICAL POST RECEIVED AN SAID GUIDEWAY TO CONTROL THE PATH OF MOVEMENT OF SAID MEMBER, MEANS ON SAID MEMBER ENGAGING A STATIONARY SURFACE DEFINED IN SAID APPARATUS AND RESILIENT MEANS MOUNTED AT THE LOWER END OF SAID POST TO PROVIDE A CUSTION FOR SAID VERTICALLY MOVABLE MEMBER IF THE MEMBER IS SUDDENLY DROPPED DUE TO A RELEASE OF FORCE APPLIED BY SAID PRINTING PAPER, SAID MOVABLE MEMBER PERMITTING SHIFTING OF THE GUIDE ROLLER VERTICALLY FROM ONE POSITION TO ANOTHER IN RESPONSE TO FORCES APPLIED THERETO BY SAID MATERIAL, BRAKE MEANS AND MEANS CONNECTING SAID BRAKE MEANS TO ONE OF SAID TENSION MAINTAINING MEANS, AND MEANS OPERATIVELY CONNECTED TO SAID GUIDE ROLLER FOR OPERATING SAID BRAKE MEANS IN RESPONSE TO VERTICAL SHIFTING MOVEMENT OF THE GUIDE ROLLER AND FOR THEREBY VARYING THE TENSION APPLIED TO SAID MATERIAL AS SAID GUIDE ROLLER SHIFTS POSITIONS, THE MEANS CONNECTING THE GUIDE ROLLER AND BRAKE MEANS COMPRISING A CAM FOLLOWER SECURED TO SAID MOVABLE MEMBER, A CAM LEVER ADAPTED TO BE MOVED BY SAID FOLLOWER AS SAID ROLLER SHIFTS POSITIONS, AND A CABLE CONNECTED TO SAID CAM LEVER AND TO SAID BRAKE WHEREBY MOVEMENT OF SAID LEVER OPERATES SAID BRAKE MEANS THROUGH SAID CABLE. 